Processing for WPCs is known to involve not only wood (in particular wood flour) but also other vegetable fibers, for example kenaf, jute, or flax.
The present invention aims to improve the WPCs known hitherto, i.e. the natural-fiber-reinforced plastics known hitherto, and in particular to reduce costs for the starting materials in the production thereof.
In the WPCs known hitherto, the proportion of wood is regularly above 20%, and there are therefore by way of example known WPCs in which the proportion of wood fiber or of wood flour is from 50 to 90%, these materials being embedded in a plastics matrix made of polypropylene (PP) or less frequently of polyethylene (PE). Because the wood is sensitive to heat, the only possible processing temperatures are below 200° C. At higher temperatures the wood suffers thermal changes and decomposition, and this alters the overall properties of the material undesirably.
Additives are also added in the natural-fiber-reinforced plastics known hitherto, in order to optimize specific properties of the materials. Examples of these properties of the materials are the bonding between wood and plastic, flowability, fire protection, coloring and, particularly for external applications, also resistance to weathering, to UV, and to pests.
It is also already known that a WPC can be produced by using a mixture of 50% of polyvinyl chloride (PVC) and 50% of wood fibers. WPCs of this type based on thermoplastically processable thermosets, such as modified melamine resin, are likewise under development, as is also the processing of products similar to wood, such as bamboo, the term used for these then being “bamboo-plastic composites” (“BPCs”). The classification “BPC” is used for WPCs where bamboo fibers have replaced wood fibers.
The advantages of the biomaterials described over traditional wood-based materials such as particle board or plywood are the unrestricted, three-dimensional moldability of the material and greater resistance to moisture. In comparison with solid plastics, WPCs offer greater stiffness and a markedly smaller coefficient of thermal expansion. The biomaterials available hitherto also have the disadvantage of lower breaking strength than sawn timber; moldings with inserted reinforcement have greater breaking strength than solid moldings and sawn timber. The water absorption of moldings with no final coating is higher than that of solid plastics moldings or moldings with film coating or with flowable coating.
It is known that the biomaterials described hitherto can be used as decking or for the production of boards, and it is equally known that WPC can be used particularly in the construction industry, the automobile industry and furniture industry, the outdoor sector for floorcoverings (patios, swimming pools, etc.), facades, and furniture, in particular as replacement for timber from tropical regions. There are also many known seating and shelving systems made of WPCs. Other applications are writing implements, containers, and household equipment, and WPC biomaterials are used in the engineering sector as profiles for electrical insulation, and in the automobile industry in particular as interior door cladding and parcel shelves.
It is noted that citation or identification of any document in this application is not an admission that such document is available as prior art to the present invention.
It is noted that in this disclosure and particularly in the claims and/or paragraphs, terms such as “comprises”, “comprised”, “comprising” and the like can have the meaning attributed to it in U.S. Patent law; e.g., they can mean “includes”, “included”, “including”, and the like; and that terms such as “consisting essentially of” and “consists essentially of” have the meaning ascribed to them in U.S. Patent law, e.g., they allow for elements not explicitly recited, but exclude elements that are found in the prior art or that affect a basic or novel characteristic of the invention.
It is further noted that the invention does not intend to encompass within the scope of the invention any previously disclosed product, process of making the product or method of using the product, which meets the written description and enablement requirements of the USPTO (35 U.S.C. 112, first paragraph) or the EPO (Article 83 of the EPC), such that applicant(s) reserve the right to disclaim, and hereby disclose a disclaimer of, any previously described product, method of making the product, or process of using the product.